Automatic resetting timer

ABSTRACT

An apparatus for timing the clean cycle of a self-cleaning pyrolytic range, terminating the clean cycle and resetting itself is disclosed. The timing device is actuated by movement of a door latch handle to latch position and is reset after a predetermined time by moving the door latch handle to its unlatched position. No undesired mechanical linkage is required that extends between the front and rear of the self-cleaning range when utilization of the circuitry disclosed is had.

. United States Patent 1191 Leach 1 51 May 29, 1973 1541 AUTOMATICRESETTING TIMER 3,648,011 3 1972 Holtkamp ..219/413 [75] Inventor: JamesA. Leach, Shelby, Ohio Primary Examiner-Bernard A. Gilheany [73]Assignee: Westinghouse Electric Corporation, Assistant Examiner p, EBell Pittsburgh, Pa- A ttorney- F. H. Henson, E. C. Arenz et al. [22]Filed: Oct. 7, 1971 [57] ABSTRACT [21] Appl. No.: 187,433

An apparatus for timing the clean cycle of a selfcleaning pyrolyticrange, terminating the clean cycle U-S. I i l and is is Clactuatedmovement of a door latch handle to latch [58] Field of Search..219/4l2,4l93,4l94, position and is reset after a predetermined time by219/4 4 3 moving the door latch handle to its unlatched position. Noundesired mechanical linkage is required that ex- [56] References C'tedtends between the front and rear of the self-cleaning UNITED STATESPATENTS range when utilization of the circuitry disclosed is had.3,410,988 11/1968 Nagel .f. ..219 492 x 4 Claims, 1 Drawing FigureAUTOMATIC RESETTING TIMER BACKGROUND OF THE INVENTION I circuitry whichprovides for automatic timing of the clean cycle and resetting of thesame by unlatching of the oven door.

2. Description of the Prior Art Present clean timer arrangements forself-cleaning ranges generally, are actuated by movement of a doorlatch' handle to a latched position. The movement to latched position ofthe latch handle is transferred to the rear of the oven by a mechanicallinkage or the like and this motion is utilized for the setting andresetting of the timer motor which dictates the time period of the cleancycle. For example, in US. Pat. No. 3,410,988, owned by a commonassignee, operation of the latch handle moves'a worm drive shaft intocontact with a timer gear. Disengagement of this mechanical contactoccurs when the latch is moved to unlatched condition and a biasingmeans moves the timing gear back to a reset position ready for the nextclean cycle.

However, as pointed out above, this arrangement requires that the timingmechanism and its actuation occur at the rear of the oven so that amechanical linkage arrangement must be provided between the latch andthe timing gear. Further, due to the expansion of the oven during anyheating cycle, a means must be provided between the front and the rearof the oven to compensatefor this expansion so as to insure a properactuation of the timing gear and an initiation of and resetting for aheat cleaning cycle.

Accordingly, it would be advantageous to provide a clean cycle timingapparatus that was initiated by latching of a latch mechanism for theoven door but which did not require a mechanical linkage extendingbetween the front and the rear of the oven and the consequent requireduse of a compensating means therefor to counter the effects of expansiondue to the oven heating. Such an apparatus would preferably therebyprovide a cleaning cycle timing arrangement of fewer parts and,therefore, much less expensive manufacture than those cleaning cyclearrangements that required the use of an actuating mechanism thatextended between the front and rear of the range.

SUMMARY OF THE INVENTION In accordance with the concepts of theinvention, an oven of heat cleaning character is provided having meansfor latching an oven cavity door, a circuit means for controlling theheating of the cavity, the circuit means including a switch which isnormally closed but is opened to terminate the heat cleaning cycle forthe oven. An electrically powered timer motor is provided to rotate acam arrangement that opens the aforementioned switch to cause thetermination of the clean cycle. An interlock switch arrangement is alsoprovided that is actuated by the latching means for the door to initiatethe cleaning cycle, this interlock switch also insuring, when the ovendoor latch is moved back to open condition, that another circuit isestablished to the timer motor through'another contact on the interlockswitch so that the timer motor will run long enough to move the camarrangement back out of engagement 2 with the interlock switch therebyreconditioning the circuit for the timer motor again so that it maydrive the cam from its initial position so that another cleaning cyclemay be subsequently initiated.

DRAWING DESCRIPTION For a better understanding of the invention,reference may be had to the preferred embodiment, exemplary of theinvention, shown in the accompanying drawing, in which:

The FIGURE represents a schematic illustration of the heat cleaning ovenarrangement which incorporates automatic timer resetting forconditioning the oven circuit for another cleaning mode thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT An oven circuit 10 isillustrated in the FIGURE that includes a bake heater 12, a speed broilheater 14, and a broil heater 16, with these elements taking the form ofresistance heaters, and disposed within an oven enclosure 18 illustratedas a dash line rectangle in the FIGURE. Also enclosed within the dashline rectangle is an anticipator heater 20 that is physically situatedadjacent a thermostat 22 so as to provide supplementary heating theretoand reduce the temperature range through which the thermostat 22 mustoperate to provide an upper temperature limiting means for operation ofthe aforementioned resistance heaters.

The thermostat 22 is a conventional hydraulic thermostat that includesnormally closed contact 24, 26 and 28, 30 which open upon a temperaturebeing reached which is preset on the thermostat 22. The opening of thesecontacts serves to interrupt the flow of electrical power to theaforementioned bake, speed broil and broil heaters so as to provide asafety feature and upper temperature limitation for the operation of theoven circuit 10. The thermostat 22 also has a lower preset temperaturewhich, when reached, causes the contacts 24, 26 and 28, 30 to close sothat bake, speed broil or broil mode of operation may continue.

The power supply for the oven circuit 10 is provided by a standardEdison three wire system, with the three wires denoted L L and N andwith240 nominal volts existing across the lines L to L and nominal voltsexisting between neutral N and either of these two lines.

Power from the L side of the power source is connected to a selectorswitch means 32 (illustrated also as a dash line rectangle), with theselector switch means 32 being mounted on the range (not shown) in aposition easily accessible to the user. Selector switch means 32includes within its enclosure a series of movable contacts which may bemoved by a dial means (not shown) so as to initiate any of the heatingor the cleaning cycle for the oven circuit 10.

More specifically, selector switch means 32 may be moved to placeheating circuit 10 into a bake, time bake broil, speed broil, clean orlatch position. As is illustrated graphically in the FIGURE, a firstseries of three contacts 33, 34 and 36 are disposed in the selectorswitch and utilized for the speed broil, bake and time bake modes ofoperation of the oven circuit 10. As is indicated by the abbreviations,the contacts 33 and 34 are in engaged position for the speed broiloperation, while the contacts 34 and 36 are in engaged condition for thebake and time bake modes of operation of oven circuitry 10. In a similarmanner contact means 38, 40, 42, and 44 provide actuation of selectorswitch means for the differing modes of operation of the oven circuitry10 as indicated by the abbreviated indications in the FIGURE. Thus, theoperator of the oven circuitry 10 may conveniently dial in that mode ofoperation which is desired for the oven circuitry 10 to undergo. Theoperation of selector switch means 32 is more precisely described in US.Pat. No. 3,549,862, owned by a common assignee. Reference may be had tothis patent for a more thorough going understanding of the operation ofthe switch means 32.

A pulsing switch 46 is also provided in oven circuitry 10 so that theoven heating means provide a pulsing heat flow to the oven cavity 18.The details of a switch of this nature are more fully covered in U.S.Pat. No. 3,440,402, owned by a common assignee. Reference may be had tothis patent if a fuller explanation of the operation of pulsing switch46 is desired.

A latch actuated circuit means 48 is provided in the oven circuit 10 soas to initiate the clean mode of operation of the oven circuit 10 when adoor latching means 50 of conventional character is moved to a latchedposition after a door 51 for oven cavity 18 has been closed. The latchoperated circuit means 48 also includes a timing motor means 52 whichterminates the heat cleaning mode and, when the door latching means 50has been moved to its unlatched position, continues running so as toreset the latch actuated circuit means 48 so that the oven circuit 10 isagain in condition so as to be capable of initiation for another cleanmode of operation.

A pair of switches 54 and 56 are physically located so as to be actuatedby a door latching means 50, the,

switches 54 and 56 being shown in the position when the latch means 50is in unlatched condition. These switches may be mounted at the front ofthe oven to eliminate the aforementioned rearwardly extending linkageand compensating means, or, if desired, may be physically located in anyother convenient area of the oven even at the rear if this isadvantageous.

The switch means 54 is a single pole, double throw switch and includes apair of contacts 58 and 60 and a switch blade 59 so that the switchblade can close on either of these contacts dependent upon the positionof the latching means 50. The switch blade 59 closes on the contact 60with the latching means 50 in unlatched condition and on the contact 58when the latch means 50 is in latched condition. Similarly, the switchmeans 56 is a two-position switch with its switch blade 61 in openposition when the latch means 50 is in unlatched condition and in closedposition with a contact 62 when the latch means 50 is in latchedcondition. Thus, the blade of switch means 54 engages the contact 60,while the blade of switch 56 does not engage its contact 62 when thelatching means 50 is in an unlatched condition; when the latch means 50is moved into a latched condition, the blades of the switches 54 and 56close against contacts 58 and 62, respectively, as motivated by thelatching mechanism 50 and/or any conventional linkage arrangementconnected between it and the switch means 54 and 56.

Timing motor 52 is a part of the latch actuated circuit means 48 andincludes a cam means 64 which is drivingly rotated thereby andpositioned so that it may contact a switch means 66 which includes aswitch blade 68 and a pair of contacts 70 and 72 so that switch means 66is a single pole, double throw switch. The contact is normally closedwith switch blade 68 because of the resilient bias on this switch blade,while the contact 72 is normally open to thereby form a normally openand a normally closed contact for the switch.

The switch means 54, S6 and 66 are connected into the latch actuatedcircuit means 48 in the following manner. A lead 74 extends downwardlyfrom a contact 76 of contact means 44 of selector switch 32, with thiscontact being electrically connectable with and, therefore, inelectrical current carrying capacity with the L side of the line bymovement of the selector switch 32 so as to place a movable contact 78of contact means 44 in engagement with contact 76. Lead 74, in turn, isin electrical connection with switch blade 68 of switch means 66. Thus,with a closed contact 70 and the oven circuit 10 in clean mode, anelectrical circuit extends between the L, side of the line through theswitch means 66 (normally closed contact 70) and switch means 56 (withthe latching means 50 in latched position) and a lead 80 extending fromthe switch blade 61 to the aforementioned pulse switch 46 and throughthe broiler element 16 and a clean thermostat 82 which is set to open atan upper temperature limit of say 1,050F so as to limit the toptemperature at which the oven circuit 10 operates during the cleaningmode.

The current flow is completed to the L side of the line through a thenclosed relay switch means 84 which, in turn, is connected to the closedcontact means 42 of the selector switch that is connected to the L sideof the power supply through a lead 86. The contact means 42 is, ofcourse, closed in the clean mode of operation due to the selector switch32 having been manipulated to the clean mode by the user of the ovencircuit 10.

In order to place the relay switch means 84 in closed condition, a relaycoil 88 is provided which is connected to the neutral side N of the linethrough the lead 90. The relay coil 88 is also connected across the Lside of the line through the aegis of a lead 92 that extends therefromto the switch means 54. With the door 51 latched, switch blade 59 isconnected to contact 58. A lead 94 extends from the opposite side ofcontact 58 and is connected to the contact 62 of switch means 56 fromthence and the contact 70 for the switch means 66. Flow of current maythen follow a path formed between the neutral N side of the line throughthe relay coil 88, switch means 54, lead 94, and lead 74 and the closedcontact means 44 to the L side of the power supply. By this arrangement,then, the relay coil 88 is actuated when the door latching means 50 ismoved to latched condition, placing the switch means 54 and 56 in closedposition relative to the contacts 58 and 62, respectively.

During the time that power is being supplied through the broil element16 for the clean mode of operation of oven circuit 10, the timer motor52 is energized. This timer motor and its cam means 64 are sized anddimensioned so as to provide a sufficiently long clean mode ofoperation, such as 45 minutes duration, to insure that all thecombustibles coating the interior of the oven enclosure 18, aredestroyed by pyrolytic action. To terminate the clean mode of operation,the cam means 64 rotates a sufficient amount so that a camming surface65 thereof engages the switch means 66. Switch blade 68 is in itsnormally closed position at this time and is moved by contact with camsurface 65 so that it engages contact 72. With switch blade 68 in thisposition, current flow from the L side of the power supply is terminatedto broil element 16 since the lead 80 is no longer energized withcontact 62 open. At the same time, the relay coil 88 is no longer placedacross neutral to the L side of the power supply because the lead 94 isnot energized. Removal of power from the relay coil 88 opens the relayswitch means 84, thus terminating a connection from the pulse switch 46to the L side of the power supply.

The latch actuated circuit means 48 includes means for resetting itselfso as to place it in a condition again for another clean mode ofoperation of the oven circuit 10. More specifically, with the switchblade 68 closed against contact 72, as moved thereto by camming surface65, the door latching means 50 is manually moved to an unlatchedcondition to permit ingress into the oven cavity 18. At this time,switch blade 61 opens while switch blade 59 moves into a closedcondition with contact 60. This provides a flow of energizing current tothe timer motor 52 since the timer motor is connected across neutral Nto the L side of the power supply line by the lead 74, the closedcontact 72,.a lead 96 extending from the contact 72 to the switch blade59 and thence to the timer motor 52 and from it through the lead 90extending to neutral N.

This circuit arrangement energizes the timer motor 52 so that it rotatesto move the cam surface 65 of cam means 64 beyond interfering urgingcontact with the switch blade 68 so that the switch blade 68 againassumes a closed position with contact 70. Movement of the switch blade68 away from contact 72, of course, terminates the closed circuitbetween neutral N and L side of the power supply so that the operationof the timer motor 52 ceases and the timer motor 52 is again in aposition so that a cleaning mode of operation may be again initiated foroven circuit 10.

It should be clear from the foregoing description that a conventionalovencircuitry has been provided with an electrical circuit arrangementwhich, in conjunction, with a door latching means, initiates andterminates the clean mode of operation and then places the oven circuitin condition for another clean mode of operation by resetting itselfafter movement of the door latching means to unlatched position.

It should also be clear to one skilled in the art that an oven circuitarrangement has been described which provides all the advantages set outfor it in the beginning portion of the description and that manymodifications could be made to the exemplary circuitry without theexercise of the inventive skill which would still fall within the spiritand scope of the description offered.

I claim: v

1. In an oven having separate cooking and heat cleaning modes ofoperation:

a. a door latch operated switch means,

b. a timer motor energized by moving said door latch operated switchmeans to a latched position.

c. said timer motor drivingly rotating a cam means,

d. said cam means engageable with another switch means having a switchblade contactable by said cam means and a pair of alternately engageablecontacts, one of saidcontacts being normally engaged by said switchblade and the other of said contact being normally open relative to saidswitch blade,

e. a heating means for said oven for operating said oven in heatcleaning mode,

f. said cam means when engaging said another switch means moving saidswitch blade against said normally open contact,

g. said door latch operated switch means also having an unlatchedposition,

h. when said latch operated switch means is moved I to said unlatchedposition and said switch blade has been moved by said cam means to aclosed position with said normally open contact, said timer motor isactuated to move said cam means out of engagement with said switchblade,

. whereby said oven is again placed in condition for the initiation ofanother heat cleaning mode.

2. In an oven heaving a door adapted to be latched during a cleaningmode of operation;

a. circuit means including a latch operated switch means having a firstposition for initiating said cleaning mode of operation and a secondposition preventing said cleaning mode of operation,

b. timing means in said circuit means for terminating said cleaning modeby operation of timing means operated switch means from a first to asecond po sition,

c. said timing means operated switch means in said second positioncompleting a portion of said circuit means for subsequent energizationof said timing means by operation of said latch operated switch means toa second position,

d. said latch operated switch means and said timing means operatedswitch means being connected in said circuit means in a two-wayarrangement so that said timing means is connected for energization onlywhen both said switch means are either in said first positions or insaid second positions whereby operation of said latch operated switchmeans to said second position after a cleaning mode of operation resultsin energization of said timing means until said timing means operatedswitch means is operated back to said first position.

3. A control arrangement for a self-cleaning oven having an oven cavitywith heating means therein, and

an oven door, comprising:

timer means for controlling the period of a cleaning cycle;

a circuit for energizing said timer means;

timer operated switch means in said energizing circuit having a firstand a second position for effecting a cleaning cycle and a timerresetting cycle, respectively;

latch operated switch means in said energizing circuit having a firstand a second position corresponding to said door being latched andunlatched, respectively;

both said switch means being connected in a two-way arrangement in saidenergizing circuit so that said timer means is energizable only whenboth of said switch means are in either said first or said secondpositions so that upon operation of said timer operated switch means bysaid timer means to said second position at the end of a cleaning cycle,operation of said timer means is terminated until said latch operatedswitch means is operated to said second position whereupon said timermeans is energized in a resetting cycle until operation of said timingmeans is again terminated by operation of said timer operated switchmeans back to said first position.

means and said latch operating switch means, both of said switch meansbeing required to be in said first positions for energization of saidheating means to be effected.

1. In an oven having separate cooking and heat cleaning modes ofoperation: a. a door latch operated switch means, b. a timer motorenergized by moving said door latch operated switch means to a latchedposition. c. said timer motor drivingly rotating a cam means, d. saidcam means engageable with another switch means having a switch bladecontactable by said cam means and a pair of alternately engageablecontacts, one of said contacts being normally engaged by said switchblade and the other of said contact being normally open relative to saidswitch blade, e. a heating means for said oven for operating said ovenin heat cleaning mode, f. said cam means when engaging said anotherswitch means moving said switch blade against said normally opencontact, g. said door latch operated switch means also having anunlatched position, h. when said latch operated switch means is moved tosaid unlatched position and said switch blade has been moved by said cammeans to a closed position with said normally open contact, said timermotor is actuated to move said cam means out of engagement with saidswitch blade, i. whereby said oven is again placed in condition for theinitiation of another heat cleaning mode.
 2. In an oven having a dooradapted to be latched during a cleaning mode of operation; a. circuitmeans including a latch operated switch means having a first positionfor initiating said cleaning mode of operation and a second positionpreventing said cleaning mode of operation, b. timing means in saidcircuit means for terminating said cleaning mode by operation of timingmeans operated switch means from a first to a second position, c. saidtiming means operated switch means in said second position completing aportion of said circuit means for subsequent energization of said timingmeans by operation of said latch operated switch means to a secondposition, d. said latch operated switch means and said timing meansoperated switch means being connected in said circuit means in a two-wayarrangement so that said timing means is connected for energization onlywhen both said switch means are either in said first positions or insaid second positions whereby operation of said latch operated switchmeans to said second position after a cleaning mode of operation resultsin energization of said timing means until said timing means operatedswitch means is operated back to said first position.
 3. A controlarrangement for a self-cleaning oven having an oven cavity wiTh heatingmeans therein, and an oven door, comprising: timer means for controllingthe period of a cleaning cycle; a circuit for energizing said timermeans; timer operated switch means in said energizing circuit having afirst and a second position for effecting a cleaning cycle and a timerresetting cycle, respectively; latch operated switch means in saidenergizing circuit having a first and a second position corresponding tosaid door being latched and unlatched, respectively; both said switchmeans being connected in a two-way arrangement in said energizingcircuit so that said timer means is energizable only when both of saidswitch means are in either said first or said second positions so thatupon operation of said timer operated switch means by said timer meansto said second position at the end of a cleaning cycle, operation ofsaid timer means is terminated until said latch operated switch means isoperated to said second position whereupon said timer means is energizedin a resetting cycle until operation of said timing means is againterminated by operation of said timer operated switch means back to saidfirst position.
 4. A control arrangement according to claim 3 including:a heating means control circuit for effecting energization of saidheating means, said heating means control circuit including said timeroperated switch means and said latch operating switch means, both ofsaid switch means being required to be in said first positions forenergization of said heating means to be effected.